Water leakage alarm system



Aug. 10, 1965 M. R. UHLIG WATER LEAKAGE ALARM SYSTEM Filed Aug. 12, 1960 FIG. 2.

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UnitedStates Patent 3,200,388 WATER LEAKAGE ALARM SYSTEM Max R. Uhlig, Granada Hills, Calif., asslgnor to Weber Aircraft Corporation, Burbank, Calif, acorporation of California Filed Aug. 12, 1960, Ser. No. 49,328

1 Claim. {CL 34il242) The present invention relates to improved signalling systems and in particular to a new and improved system for producing a signal in response to an accumulation of water under undesirable conditions such as, for example, below washing machines and other similar appliances.

Briefly as illustrated, the system involves an alarm comprising a transformer having its primary winding connected to a suitable A.C. source and having its secondary winding connected to a pair of electrodes. Normally, a substantially non-conductive path exists between such electrodes but such path is made sufficiently conductive in the presence of water to load the transformer and produce a relatively large amount of magnetic flux in the core of the transformer. Such relatively large flux causes vibration of a spring-mounted armature to produce a noise signal. This noise signal is amplified by a sounding board effect which is accomplished by mounting a transformer core on a suitable resonating housing.

It is therefore an object of the present invention to provide an improved system of this character in which water leakage produces a sound alarm.

Another object of the present invention is to provide a system of this character in which a signal alarm may be actuated by one of a plurality of electrode systems placed under corresponding appliances where water leakage may possibly be expected.

Another object of the present invention is to provide a system of this character which is relatively simple and inexpensive.

Another object of the present invention is to provide a system of this character in which the electrodes, after wetting, may be reconditioned for subsequent use.

Another object of the present invention is to provide a system of this character in which the sensing element is supplied with relatively low voltage so as to minimize any danger from electric shock or fire hazard.

The features of the present invention which are believed to be novel are set forth with particularity in the appended claim. This invention itself, both as to its organization and manner of operation, together with further objects and advantages thereof, may be best understood by reference to the following description taken in connection with the accompanying drawings in which:

FIGURE 1 illustrates a system embodying features of the present invention in relationship to an appliance illustrated for purposes of exemplificaton as a closed washing machine.

FlGURE 2 illustrates the electrical circuitry and general physical arrangement of the electrical elements in the system shown in FIGURE 1.

FIGURE 3 is generally a sectional view taken on the line 33 in FIGURE 2.

Referring to the drawings, FIGURE 1 illustrates the system associated with a closed washing machine although it is understood, of course, that the system may be associated with any other appliance or apparatus which in use may possibly leak a fluid. For example, the system may be used to detect leakage of fluid from a mal functioning appliance such as a hot water heater, an elec tric dish Washer, a Wash basin or the like. The present system is particularly useful in these instances since due to faulty fabrication, installation or wear, it is observed that appliances of this class are often located in such a manner that small leaks are not visible but remain unnoticed until extensive damage occurs. These conditions are obviated by the present system which senses the water leakage and causes an audible alarm to be produced.

The water-sensing means is positioned, for example, in a tray or water receptacle 11 and such sensing element comprises a pair of electrodes 12 and 13 preferably in the form of cantilever-supported spring elements having adjacent ends thereof secured in an insulating block 14 as, for example, by molding the spring electrode elements 12 and 13 in a plastic block 14.

Normally, there is a relatively large resistance or impedance between such electrodes 12 and 13 and this may be established by providing a water-soluble substance 15 between the electrodes 12 and 13 to normally maintain the same spaced apart. When there is an accumulation of water in the receptacle 11, the substance 15, which may, for example, be sugar, melts or dissolves and the resiliency of the spring elements 12 and 13 causes engagement between the electrodes 12 and 13 to complete a circuit to the alarm device described later. The substance 15 may take other forms; for example, the same may be a water-deformable spacer made from cellulose fibres impregnated with a suitable salt that dissolves rapidly in water to form a conductive electrolyte. In this latter instance the electrodes 12 and 13 may not be resilient but simply comprise rigidly spaced electrodes. When the substance 15 comprises porous fibres impregnated with common sodium chloride salt, the same may be re-used after drying, in which latter case it offers a high impedance which degenerates into a sufiiciently low impedance when wetted.

These electrodes 12 and 13, as illustrated in FIGURE 2, are connected to leads 12A and 13A which sealingly extend through a side wall of the pan or receptacle 11 and such leads 12A and 13A are connected to opposite terminals of a low-voltage secondary winding 20 of a combined transformer and alarm 21. Preferably one of such leads 12A, 13A is grounded, lead 13A being shown grounded for this purpose. The primary winding 22 of transformer 21 has its terminals connected to a conventional Wall plug 23 insertable in the usual -volt household receptacle.

These windings 20 and 22 are wound on a common laminated magnetic core member 24 which is aflixed as, for example, by a rivet 25 to a sound-resonating housing 26. This housing 26 in turn may be resiliently mounted on a wall adjacent the appliance 10. The core member 24 is an open-frame core member having four legs 24A, 24B, 24C and 24D arranged in a generally rectangular pattern but with the leg 24C shortened to provide the air gap 24E between legs 24C and 24D. A spring-mounted armature 27 is mounted adjacent such air gap 24E on the free end of a cantilever-supported spring 28, the spring 28 having one end thereof afiixed to the core member 24 as, for example, by a screw 30 with a spacing washer 31 between the spring element 28 and the core member 24.

In operation of the system, in the absence of water in Le. a relatively high current flows through the windings 20 and 22, with the result that a relatively high magnetic flux is established in the core 24 and particularly in the ,air gap 24Eto-cause the armature 27 to be attracted ,in the direction of the air gap. However, such movement of the armature 27 is controlled by the spring 28 such that the armature 27 vibrates, and in some cases periodically contacts the core legs 24C and 24D to produce a sound or noise which is transmitted through the core to the sound-resonating chamber 26, the latter serving genenerally as a sounding board for producing an enhanced sound alarm. Thus, a persons attention is directed to water leakage and he has an opportunity to remedy the same. The armature 27 vibrates under the conditions mentioned above since the core 24 has a magnetic flux which isperiodically of maximum value and of minimum value in accordance with the maximum and minimum values of the alternating current wave flowing through the primary winding. When such current builds up to its maximum value, the flux increases and the armature 27 .is attracted against the action of spring 28; and when the current decreases, the flux decreases to a value where it is insuflicient to overcome the force of spring 28 and such spring 28 causes the armature 27 to move to its position shown in FIGURE 2. Since the alternating current is.

periodic there will be a periodic attraction of the armature 27 causing it to vibrate.

The system will operate, with one or more of such electrode systems 12, 13 connected to the secondary winding 20. This is illustrated in FIGURE 2 wherein 1 like water receptacles 11A andllB each having like electrodes therein are connected by corresponding leads 12B,

13B and 12C, 13C to opposite terminals of secondary winding 20. These receptacles 11A, 1113 may be placed under different appliances and in such case it will be appreciated that when there is an accumulation of water in any one of the receptacles 11, 11A or 11B, an audible alarm signal is developed as previously described. I

While the particular embodiments of the present invention have been shown and described, it will be obvious to those skilled in the art that changes and modifications may be made without departing from this invention in its broader aspects and, therefore, the aim in the appended claim is to cover all such changes and modifications, as fall within the true spirit and scope of this invention.

I claim:

A water leakage alarm system of the character described comprising: a transformer having a primary and a secondary winding, each ofsaid windings being wound on an open magnetic core, said magnetic core having an air gap therein, a vibratory armature supported on said core adjacent said air gap, and impedance means having its impedance changeable in the presence of water connected to said secondary winding to control magnetization of said core and vibration of said armature, said magnetic corehaving four legs arranged generally in a rectangular pattern, a resonant housing secured to one of said legs, said air gap being in a leg of said magnetic core which is opposite to said leg to which said housing is secured, said armature being supported on said leg in which said air gap is located, said vibratory armature bridging said air gap and being normally spaced from said air gap with the armature being attracted to said core member when said impedance means is changed in the presence of water to produce a sound which is transmitted through the core structure to said resonant housing which encompasses said core structure and said armature.

References Cited by the Examiner UNITED STATES PATENTS 1,048,913 12/12 Stuart 34040l 1,271,865 7/18 Dodds 340242 1,602,300 10/26 Grant 340--244 1,622,862 3 27 Detmers. 1,979,127 10/ 34 Warrick. 2,028,263 1/36 Warrick 340-384 XR 2,050,623 8/36 Metting 2006 1 .04 XR 2,342,730 2/ 44 Goodbar 340-393 2,757,365 7/56 Perez 340401 2,804,609 8/57 Sussman 34040l XR FOREIGN PATENTS 22,394 10/ 14 Great Britain. 380,383 9/ 32 Great Britain. 464,149 4/37 Great Britain.

NEIL C. READ, Primary Examiner. ELI I. SAX, ROBERT H. ROSE, Examiners, 

